1. 1 Intro to Organic Chemistry Part 06: The Cycloalkanes Chapter 10

2. 2 Remember this???? Hydrocarbons Aliphatic Alkanes Aromatic CycloalkanesAlkenes Alkynes Unsaturated Saturated

3. 3 Part 06 Cycloalkanes Cycloalkanes –Saturated hydrocarbons –Have one or more rings –Also called alicyclic compounds

4. 4 Part 06 Cycloalkanes Structure of cycloalkanes –Rings form regular polygon structures Triangle, square, pentagon, etc. –Each corner of polygon represents a carbon atom –General formula: C n H 2n Not C n H 2n+2 because, when a ring forms, the alkane loses 2 H at its end.

5. 5 Properties of cycloalkanes –Similar to alkanes Nonpolar Relatively inert –Different from alkanes Alkanes have free rotation around C-C single bonds –Lower member cycloalkanes (C 3 to C 7 ) do not & are more rigid, planar structures –Attempts at bond rotation would cause the ring to break –Higher cycloalkanes less rigid »Very large rings (C 25 and up) behave like straight- chain alkanes.

6. 6 Part 06 Cycloalkanes Begin at three carbons –Smallest possible stable ring –Molecular formula: –Structural formula: –Name: C3H6C3H6 CH 2 cyclopropane

7. 7 C HH C C H H H H Cyclopropane Complete structural formula

8. 8 Cyclopropane Skeleton structure Each corner represents a carbon atom (2 H attached to each one)

9. 9 Cycloalkane with 4 carbon atoms –Molecular formula: –Name: –Structural formula: –Skeleton structure:

10. 10 Cycloalkane with 5 carbon atoms –Molecular formula: –Name: –Structural formula: –Skeleton structure:

11. 11 Cycloalkane with 6 carbon atoms –Molecular formula: –Name: –Structural formula: –Skeleton structure:

12. 12 Cycloalkane Nomenclature Attach prefix cyclo- to the name of the corresponding open chain hydrocarbon having the same number of carbons as the ring If substituent(s) present, number the ring in such a way as to give the substituent groups the lowest possible numbers Cycloalkanes can also be substituent groups –Named like the alkyl groups, but with the cyclo- prefix –One less hydrogen than cycloalkane

13. 13 Name the following Br F Cl H – C – C – C – C – C – C – H H H H NO 2 H H H H H H H If there is only one substituent attached to the cycloalkane, it is not numbered.

14. 14 Draw the skeleton structure for the following: 1) iodocyclopropane

15. 15 Draw the skeleton structure for the following: 2) propylcyclopentane

16. 16 Draw the structural formula for the following: 3) 1 – amino – 2,3 – dicyclopropyl – 4 - methylheptane

17. 17 Cycloalkane isomers Cycloalkanes are “essentially” planar Location of substituents –Both on same side of ring: cis isomer cis (Latin): “on this side” –One above & one below: trans isomer trans (Latin): “across”

18. 18 Example: Draw the cis and trans isomers of 1,2- dichlorocyclopropane. Cl cis trans

19. 19 Practice: Draw the cis and trans isomers of 1,2-diaminocyclobutane. NH 2 cis NH 2 trans

20. 20 Practice: Draw the cis and trans isomers of 1-ethyl-3-bromocyclopentane. C2H5C2H5 Br cis C2H5C2H5 Br trans

21. 21 Name the following: C4H9C4H9 C4H9C4H9 cis-1,4-dibutyl cyclohexane C4H9C4H9 C4H9C4H9 trans-1,4-dibutyl cyclohexane

22. 22 Name the following: trans-1-hexyl-4-isopropylcyclohexane C 6 H 13 CH CH 3

23. 23 Homework: Due Tomorrow 10/06/10 Page 21-22 (binder): 1-12

24. 24 Homework: Due Tuesday 10/12/10 Page 356-357 (book) # 33, 34, 35, 37, 39c, 40c (50 points)

25. 25 Quiz: Wednesday 10/13/10 Isomers & Cycloalkanes 50 points